Why Are Red-breasted Nuthatches Irrupting?

There can be no doubt that this year is an irruption year for Red-breasted Nuthatches. Sitta canadensis isn’t just irrupting out of its far northern home but exploding southward, with reports in every southern state except for Florida, including birds on the outer banks of North Carolina, on Grand Isle, Louisiana, in a suburb of Atlanta, and on the Gulf Coast of Texas. Bird bloggers from Wisconsin to Massachusetts have noticed the irruption and blogged about it. But just how much have Red-breasted Nuthatches shown up since their irruption started in August? Check out this graph adapted from eBird that shows the frequency of sightings in the United States in 2012 – Red-breasted Nuthatches are showing up on birders’ checklists just over sixteen percent of the time!

frequency of Red-breasted Nuthatch sightings in the United States, January-September 2012

But why are the nuthatches irrupting? The usual understanding of why irruptions of birds – from Red-breasted Nuthatches to Snowy Owls – occurs is that there is a shortage of food. No lemmings left in the north? Birders are delighted by Snowy Owls. No cones from which Red-breasted Nuthatches gather seeds? Birders across the United States are delighted by the “yank-yank” of Red-breasted Nuthatches on sixteen percent of their outings.

Red-breasted Nuthatchat Jones Beach State Park, New York

Ron Pittaway’s famous winter finch forecast includes some some non-finch irruptives, including Red-breasted Nuthatch. This year’s forecast, which, as always, is Ontario-centric, says the following about red nuts:

A widespread irruption of this nuthatch beginning in mid-summer indicated a cone crop failure in the Northeast. Most will leave the eastern half of the province for the winter, but some will probably remain in northwestern Ontario where cone crops are much better.

No cones, no nuthatches – they irrupt! But could the widespread nature of this irruption and the sheer number of birds indicate that something else is going on? The cones that nuthatches are dependent upon are apparently notorious for having a boom-and-bust cycle. If they are a bust this year, as Pittaway indicates that they are at least in Ontario, then last year it is likely that they were booming. This article discusses the heavy cone crop in Maine last year on red spruce, balsam fir, and larch, and Ron Pittaway’s forecast from last year said “cone crops are excellent and extensive across much of the boreal forest and the Northeast” and that nuthatches had “very little southward movement.”

Red-breasted Nuthatchat Jones Beach State Park, New York

In December of last year Clare Kines wrote a post here on 10,000 Birds about the cause of the massive Snowy Owl irruption many birders were lucky enough to experience. He explained that the irruption was not just caused by the drop in lemming populations that are the main prey of Snowy Owls but by the huge number of lemmings that were around just prior to the bust:

Snowy Owls produce large broods of up to 14 chicks on years when lemmings are plentiful. A brood of nine chicks will be fed something in the order of 1500 lemmings from the time they are hatched until they are independent. Remember that friend of mine that saw 17 breeding pairs of Snowy Owls in a single valley? If they each raised nine owlets, the owlets alone would have eaten over 25,000 lemmings from that valley.

So this was a good summer for lemmings, a very good year. They were everywhere, including a couple of them that inhabited a cage in my house for a while (they were released back where they were caught). They actually make very good pets, becoming very tame quite quickly. And because it was a good year for lemmings it was a very good year for Snowy Owls, who produced large broods. As these broods have grown into juvenile birds there is more and more competition for fewer lemmings and they begin to disperse farther and farther afield, resulting in the irruption that many of you are enjoying now. I think that you’ll find that most of the Snowy Owls you are seeing are juveniles.

Do nuthatches have the same boom-type population burst because of good conifer crops? Yes and no, or at least, that is what I theorize. Red-breasted Nuthatches rely on seeds from conifers as a staple when they winter in the far north. Young birds are fed on what all young birds are fed on – lots of protein. Bugs, caterpillars, and other assorted creepy-crawlies are what young nuthatches get from their parents. But when winter came to the far north last year their diet, like their parents’ diets, changed to seeds from cones. And because cones were abundant nearly everywhere in their range, they had plenty to eat. And because they had plenty to eat they did not have to travel great distances to find food, which is the most dangerous undertaking a bird, particularly a young bird, experiences. That means there were a lot more nuthatches around this spring to breed and that means that there are lots and lots more nuthatches to irrupt across the United States right now.

Thank a pine cone. Or a spruce cone. Or a larch cone.

Red-breasted Nuthatch at Van Saun Park, New Jersey

I don’t want to understate my lack of scientific credentials, which is total. Also, I don’t really trust that eBird data for previous irruption years – which seem to indicate that this year is a much larger irruption than past years – is entirely accurate, simply because many more people are using eBird now than in past years and the number and quality of checklists entered into eBird is up. Anecdotal evidence seems to indicate that this irruption year is larger than most but I would like to see some rock-solid empirical data. If anyone has anything further to add, or wants to scold me for my ignorance, please feel free to have at it in the comments.

Corey is a New Yorker who lived most of his life in upstate New York but has lived in Queens since 2008. He's only been birding since 2005 but has garnered a respectable life list by birding whenever he wasn't working as a union representative or spending time with his family. He lives in Forest Hills with Daisy, their son, Desmond Shearwater, and their indoor cat, B.B. His bird photographs have appeared on the Today Show, in Birding, Living Bird Magazine, Bird Watcher's Digest, and many other fine publications. He is also the author of the American Birding Association Field Guide to the Birds of New York.

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31 Comments

Jochen

October 01, 2012 10:16:06 am

They are irrupting to increase the chance of one making it across the Atlantic and into my Heidelberg backyard alive.
In my honest opinion.

One more reason why everyone should be using eBird vigorously. As Cory rightly says, some of the historical data on eBird is suspect because its uses has blossomed so much in just the last several years. But if we all keep at it by recording all our sightings, the next irruption of RBNU will have comparable data for this year and subsequent “down” years. Citizen science for the win!

Data from bird banding and migration watches (like the morning flight watch in Cape May) might help answer the question of how big this year’s irruption is compared to those in past years, but I’m not sure if that data is easily accessible to the general birding public. It would be interesting to see the numbers from those sorts of operations, though.

I’ve already seen two Red-breasted Nuthatches in my neighborhood this fall (which is quite extraordinary considering that I’d previously only seen one here in the past five years).

I’ve noticed more in the Boise area this year than ever before. I’ve been hearing them even in my suburban Meridian, Idaho area, which is usually very limited in the variety of birds. What might this suggest for other winter finches? Bring on the Redpolls and Crossbills!

@Jason: Yeah, the last several years have been good but I was hoping to get some kind of historical perspective. And you know what is cool about the chart you linked? Look under the “total” tab and see that 2010 looks like many more birds actually showed up though they were apparently more widespread in 2007.

After reading this article a few days ago, I have done a quick tour of my yard after work. Yesterday it was a flock of yellow rumped warblers. Today, there was one red-breasted nuthatch out front. Thanks for the impetus to go looking!

Two years ago, I regularly saw RBNUs at my local (Northern VA) parks, starting in late October and staying around through March-April. Last year there were none. I wondered why, and noticed that there were no new cones on the pines – they all looked dried up. I assumed that any RBNUs that came through had kept on going. This year, there are again no new pine cones on the park trees, but the RBNUs arrived in early September (in great numbers) and are staying around. I doesn’t appear that there is a bounty of cone seeds to feed on here either, so I wonder how they will fare? I’d speculate that this might be a population crash year for RBNUs. I hope not, they are one of my favorites.

Oh, by the way Corey, great shots of the Nuthatches! I especially like the first one with the little guy on top of the cone! Here is a graph of the number of RBNUs per 100 party hours of Christmas Bird Counts from 1960 to 1985.

In my South Houston (Pearland) suburb, I have seen lots of RBNU today, 10/20/12, at my bird feeder. The last time we saw any this far south along the Gulf Coast, was about 12-15 years ago. We are Very excited and hope they stay all winter.

We’ve never recorded them here on Dewees Island, and we have hand entered bird surveys from the last 20 years. Only one was ever recorded, in January of 2011. This year there is at least one pair on the island and probably two, with repeated sightings for almost a month. Thanks for all the great info– I am linking to your blog from the DeweesIslandBlog.

Saw several red breasted nuthatches at my feeder today, along with the flocks of chicadees and tufted titmouse. I live in suburban Maryland and didn’t see them last year at the feeder. They are very quick – they just grab a sunflower seed and fly away, then return again and again and again…never staying for more than a quick second.

From Austin Texas 78709: November 2012 – December 2012. Weekend bird observations – on my backyard bird feeder (sunflower seeds from HEB) and environs pairs of Red-breasted Nuthatches every weekend coming to the feeder and slinking up and down the ash junipers for the last six weeks. No more than 2 at a time always accompanied by Carolina Chickadees and Titmice. They appear multiple times throuoghout the day, are easy to approach, and call quite frequently. These sightings can either be of one pair returning or multiple pairs returnng or passing by. Have been living in this location since 2004 and these are the first sightings of this species. Deja vu is this season in the air ater living in Minnesota for 12 years some time ago.-TS

December, 2012, here in Matagorda County, Texas, the Red-breasted Nuthatches started appearing at my Sunflower Seed Feeders right about the time Hurricane Sandy was hitting the Northern States. WOW! This is a new bird! I had to go online to find it’s ID since this is an unfamiliar species to the backyard. The regular Chickadees and Titmouse are not particularly happy since the Nutchatches moved in being so numerous. They wait for their chances to sneak in at four feeders, although, I’m happy to have them all! By the way, I am still seeing Hummingbirds, so, also, have to keep those feeders supplied.

I first sighted these birds two summers ago on an island of the coast of the Lower North Shore of Quebec (Near Labrador) and now they are here by the thousands! This is the first winter we have seen them staying here, and my father just reported to me that farther up here in the woods that he has seen dozens of them dead on the forests floor. My gathering is that they are freezing to death. So sad cause they are a pleasure to watch and they love my homemade suet.